Issue #20802 has been reported by javanthropus (Jeremy Bopp). ---------------------------------------- Bug #20802: It is possible to set the encoding of an IO instance to one that requires binmode when binmode is not set https://bugs.ruby-lang.org/issues/20802 * Author: javanthropus (Jeremy Bopp) * Status: Open * ruby -v: ruby 3.3.4 (2024-07-09 revision be1089c8ec) [x86_64-linux] * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- I don't know what problems this may cause, but there are guards against setting the encoding of an IO instance to one such as UTF-16LE when the IO instance is not set to binary mode. Here is a method to bypass those guards: ```ruby f1 = File.open('/dev/null') f2 = File.open('/dev/null') f1.binmode f1.set_encoding('utf-16le') f2.set_encoding('utf-8') f1.reopen(f2) f1.binmode? # <= false f1.external_encoding # <= Encoding::UTF_16LE ``` -- https://bugs.ruby-lang.org/